Added _repr_jpeg_() for IPython display_jpeg

Tests/test_file_jpeg.py

@@ -922,6 +922,19 @@ def closure(mode, *args):
             im.load()
             ImageFile.LOAD_TRUNCATED_IMAGES = False
 
+    def test_repr_jpg(self):
+        im = hopper()
+
+        with Image.open(BytesIO(im._repr_jpg_())) as repr_jpg:
+            assert repr_jpg.format == "JPEG"
+            assert_image_equal(im, repr_jpg)
+
+    def test_repr_jpg_error(self):
+        im = hopper("F")
+
+        with pytest.raises(ValueError):
+            im._repr_jpg_()
+
 
 @pytest.mark.skipif(not is_win32(), reason="Windows only")
 @skip_unless_feature("jpg")

src/PIL/Image.py

@@ -633,19 +633,36 @@ def _repr_pretty_(self, p, cycle):
             )
         )
 
-    def _repr_png_(self):
+    def _repr_image(self, format):
         """iPython display hook support
 
+        :param format: Image format.
         :returns: png version of the image as bytes
         """
         b = io.BytesIO()
         try:
-            self.save(b, "PNG")
+            self.save(b, format)
         except Exception as e:
-            msg = "Could not save to PNG for display"
+            msg = f"Could not save to {format} for display"
             raise ValueError(msg) from e
         return b.getvalue()
 
+    def _repr_png_(self):
+        """iPython display hook support for PNG format.
+
+        :returns: png version of the image as bytes
+        """
+        return self._repr_image("PNG")
+
+    def _repr_jpg_(self):
+        """iPython display hook support for JPEG format.
+
+        :returns: jpg version of the image as bytes
+        """
+        return self._repr_image("JPEG")
+
+    _repr_jpeg_ = _repr_jpg_
+
     @property
     def __array_interface__(self):
         # numpy array interface support